Begin updating serde such that it can read the yaml test files

eth2/types/src/chain_spec.rs

@@ -2,6 +2,7 @@ use crate::*;
 use bls::Signature;
 use int_to_bytes::int_to_bytes4;
 use serde_derive::Deserialize;
+use test_utils::u8_from_hex_str;
 
 const GWEI: u64 = 1_000_000_000;
 
@@ -57,6 +58,7 @@ pub struct ChainSpec {
     pub far_future_epoch: Epoch,
     pub zero_hash: Hash256,
     pub empty_signature: Signature,
+    #[serde(deserialize_with = "u8_from_hex_str")]
     pub bls_withdrawal_prefix_byte: u8,
 
     /*

eth2/types/src/fork.rs

@@ -1,4 +1,4 @@
-use crate::{test_utils::TestRandom, ChainSpec, Epoch};
+use crate::{test_utils::{fork_from_hex_str, TestRandom}, ChainSpec, Epoch};
 use int_to_bytes::int_to_bytes4;
 use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
@@ -12,7 +12,9 @@ use test_random_derive::TestRandom;
     Debug, Clone, PartialEq, Default, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom,
 )]
 pub struct Fork {
+    #[serde(deserialize_with = "fork_from_hex_str")]
     pub previous_version: [u8; 4],
+    #[serde(deserialize_with = "fork_from_hex_str")]
     pub current_version: [u8; 4],
     pub epoch: Epoch,
 }

eth2/types/src/test_utils/mod.rs

@@ -2,6 +2,7 @@
 mod macros;
 mod generate_deterministic_keypairs;
 mod keypairs_file;
+mod serde_utils;
 mod test_random;
 mod testing_attestation_builder;
 mod testing_attestation_data_builder;
@@ -17,6 +18,7 @@ mod testing_voluntary_exit_builder;
 pub use generate_deterministic_keypairs::generate_deterministic_keypairs;
 pub use keypairs_file::KeypairsFile;
 pub use rand::{prng::XorShiftRng, SeedableRng};
+pub use serde_utils::{fork_from_hex_str, u8_from_hex_str};
 pub use test_random::TestRandom;
 pub use testing_attestation_builder::TestingAttestationBuilder;
 pub use testing_attestation_data_builder::TestingAttestationDataBuilder;

eth2/types/src/test_utils/serde_utils.rs

@@ -0,0 +1,28 @@
+use serde::{Deserialize, Deserializer};
+use serde::de::Error;
+
+pub fn u8_from_hex_str<'de, D>(deserializer: D) -> Result<u8, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let s: String = Deserialize::deserialize(deserializer)?;
+
+    u8::from_str_radix(&s.as_str()[2..], 16).map_err(D::Error::custom)
+}
+
+pub fn fork_from_hex_str<'de, D>(deserializer: D) -> Result<[u8; 4], D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let s: String = Deserialize::deserialize(deserializer)?;
+    let mut array = [0 as u8; 4];
+    let decoded: Vec<u8> = hex::decode(&s.as_str()[2..]).map_err(D::Error::custom)?;
+
+    for (i, item) in array.iter_mut().enumerate() {
+        if i > decoded.len() {
+            break;
+        }
+        *item = decoded[i];
+    }
+    Ok(array)
+}